Utilities Center

Water Intake Calculator

How much water should you drink?

Estimate your daily water intake goal from your body weight and exercise level, shown in litres, ounces and glasses.

Weight (kg)
Daily exercise (minutes)
Litres
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Ounces
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Glasses (250 ml)
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About the water intake calculator

Hydration needs vary from person to person and depend on body size, activity, climate and diet. A common guideline is roughly 35 millilitres of water per kilogram of body weight per day, with extra water added for exercise to replace fluid lost through sweat.

This calculator applies that guideline: it takes your weight and the minutes you exercise each day, then estimates your daily water goal in litres, US fluid ounces and 250 ml glasses. Use it as a starting point and adjust for heat, altitude, pregnancy or individual needs.

The estimate

  • Base: 35 ml × body weight (kg)
  • Exercise: + 350 ml per 30 minutes of activity

How to use the water intake calculator

  1. Enter your weight

    Use kilograms or pounds — switch units as needed.

  2. Add daily exercise minutes

    Enter how many minutes you typically exercise per day.

  3. Read your goal

    See your daily water target in litres, ounces and glasses.

Frequently asked questions

Does the 8-glasses-a-day rule apply to everyone?
No. It is a rough average. Your real need depends on weight, activity, climate and health. This calculator personalises the estimate to your weight and exercise.
Should I drink more when I exercise?
Yes. You lose water through sweat, so the calculator adds about 350 ml for every 30 minutes of activity. In hot or humid conditions you may need even more.
Does coffee or tea count?
Yes — all fluids contribute to hydration, though water is the best calorie-free choice. Foods with high water content (fruit, vegetables) also count.
Is this calculator free?
Yes — free, no sign-up, and all maths runs in your browser.

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